FIG. 21 shows the configuration of an analyzing device of the prior art in which light from a sample set on a test piece is captured by a photo detector element through an optical system and concentration information is obtained. In the analyzing device of the prior art, light from a light source 2 such as an LED is emitted to a test piece 1 on which the sample is set. Further, scattered light, transmitted light, or reflected light from the test piece 1 is captured by the photo detector element such as an image sensor 5 through the optical system that is made up of a lens 3, a diaphragm 4, and so on. The concentration of a sample 7 set on the test piece 1 is quantified by a received light quantity 6 of the photo detector element (e.g., see Japanese Patent Laid-Open No. 7-5110).
As shown in FIGS. 22A to 22C, in this analyzing device, a received light quantity distribution 10 (see FIG. 22C) of the photo detector element is determined by the product of a light quantity distribution 8 (see FIG. 22A) of the light source 2 relative to a detected wavelength and a scattered light (transmitted light or reflected light) characteristic 9 (see FIG. 22B) of the sample 7. In this case, when the light quantity distribution 8 of the light source 2 does not fluctuate, the concentration of the sample 7 may be calculated by the received light quantity of the photo detector element and the calculated concentration may be used as a measured value. Generally, the light source 2 is a narrow-range light source such as a monochromatic LED.